Topic: Jet sizes for 810cc motor

[Seamus]

Hi All,
Can anyone more experienced than me offer a start guide for an overbored CB 750K1 motor? I believe that my engine has been fitted with CB350 pistons and bored to suit. The set up is standard from there. (All performed before I got the bike)
I guess that I will probably have to alter the jets/slides in the carbs to compensate for the modification. I recon that this must have been done before (I did a search without any luck) and hope that some wise person can help me out.
Guidance appreciated
Thanks
Seamus

[Jerry Rxman Griffin aka MuthaF'er]

Seamus,

I'm running 115 mains with my Yoshi 810, Yoshi Daytona cam (high rpm hp cam), stock carbs, Kerker exhaust. I THINK my needles are in the stock position. HOWEVER I'm also at 7000 feet elevation. If you have 350 pistons they will have a very tall dome with high compression. Probably a real 810 kit. Pistons look more flat top. If you have a high perf cam that provides more mid range HP than mine you may also need to lower your needle clips thus raising the needles for more mid range fuel delivery.

Jerry

[Seamus]

Thanks Jerry. I have the 350 pistons with the dome. I am not sure of the cam, but believe that it is standard (no markings). The bike is running a standard airbox and 4 pipe exhaust (300 series).
Seems to run OK, but I have only managed 5 mikes since finishing and not opened it up yet as I am waiting for things to settle down. No choke required to start, but it has been warm lately. I just wanted some basic advice on which way to go. I will see how it runs on standard jetting, then go down to 115 if necessary and play with needle positions after that.
Thanks again
Seamus